string::substr()简介

std::basic_string::substr

C++

Strings library

std::basic_string

basic_string substr( size_type pos = 0, size_type count = npos );

Returns a substring [pos, pos+count). If the requested substring lasts past the end of the string, or if count == npos, the returned substring is [pos, size()).

Parameters

pos　　　position of the first character to include

count　　length of the substring

Return value

String containing the substring [pos, pos+count).

Exceptions

std::out_of_range if pos > size().

Complexity

Linear in count

Example

#include <string>
#include <iostream>
 
int main()
{
    std::string a = "0123456789abcdefghij";
 
    std::string sub1 = a.substr(10);
    std::cout << sub1 << '\n';
 
    std::string sub2 = a.substr(5, 3);
    std::cout << sub2 << '\n';
 
    std::string sub3 = a.substr(12, 100);
    std::cout << sub3 << '\n';
 }

Output:

abcdefghij
567
cdefghij